It is a mixed bag, but definitely improving. Some experiences: From Holland, It was impossible to do an online booking a ticket to Italy. Only possible via phone, or as separate legs. For long journeys with changeovers watch out that you don’t get stuck halfway due to a missed connection. From NL, London, France, Germany is easily reachable, as well as Barcelona. I took a sleeper train to Stockholm last Christmas, we had delays, but made it in time. In general if you have a long distance leg, it’s best to have it at the start of your journey so you don’t miss it.

Railways do have single points of failure. A single disruption on a key piece of track can disrupt service for hours, even days. This is less of an issue with air travel, there’s usually other airlines, and alternative routes.